Apollo 13

By the spring of 1970 the Moon had become, astonishingly, ordinary. Nine months earlier Apollo 11 had drawn what was probably the largest television audience in human history; Apollo 12 had gone back and landed again. So when Apollo 13 lifted off from Florida on 11 April 1970, public interest had fallen so sharply that the American networks did not carry the crew's television broadcast from space live. Somewhere beyond the atmosphere, three men gave a cheerful guided tour of their spacecraft to an audience that, unless you counted the families sitting in a room at Mission Control, scarcely existed. The crew was commanded by James Lovell, an experienced astronaut who had already flown round the Moon without landing on it. Fred Haise was the lunar module pilot. The third seat had changed hands only days before launch: Ken Mattingly had been exposed to German measles and had no immunity, and the doctors would not clear him unless he could show he would not fall ill in flight. He could not, so Jack Swigert was moved up from the backup crew, trained in parallel in case of exactly this — the kind of contingency NASA planned for meticulously and hated having to use.

The spacecraft came in two joined halves, and their names would soon become famous. The command module Odyssey was the cone the crew launched in, lived in and would come home in; behind it sat the service module, carrying the engine, the oxygen tanks and the fuel cells that made the ship's electricity and, as a by-product, its drinking water. Docked to the front was the lunar module Aquarius, a thin-walled, spidery craft built for one job: to carry two men down to the surface and back up. The launch was not perfect: one engine on the second stage shut down early and the others burned longer to compensate, which was unsettling but not dangerous. After that the flight settled into the methodical rhythm every Apollo crew knew — checklists read aloud, numbers called down to Houston, small corrections to keep the ship on its trajectory towards a Moon still three days away. Provided that nothing broke, the landing was on.

About fifty-six hours into the flight, Houston asked the crew to do a routine housekeeping job: a "cryo stir". The oxygen and hydrogen in the service module tanks were held as super-cold liquid and tended to settle into layers, so small fans inside each tank were switched on now and then to mix the contents and give accurate readings. Swigert flipped the switches. Number two oxygen tank exploded. The cause was traced back, painstakingly, through years of paperwork. That particular tank had been dropped during earlier handling on the ground. More seriously, its internal thermostatic switches had never been upgraded to match a higher-voltage ground power supply, so during a pre-flight test the switches had failed to protect the wiring and the insulation had been burned away. The result was bare wire sitting inside a tank of liquid oxygen — an accident waiting for a spark. When the fans turned, it found one.

The crew felt a bang and saw the ship shudder. Swigert's report to Houston is usually rendered as "Okay, Houston, we've had a problem here", with Lovell repeating it a moment later; the famous film line reverses the tense, and the exact wording is best treated as reported rather than quoted with confidence. Whatever was said, the numbers on the ground turned bad within minutes. The explosion had blown a panel clean off the side of the service module, destroyed one oxygen tank and damaged the other, which was now venting its contents into space. That mattered far more than the air itself: the fuel cells needed oxygen to make electricity and water, so as the oxygen drained away the command module was losing its power, its heat and its drinking supply all at once. Lovell, looking out of the window, could see the gas escaping in a great pale plume. The landing was abandoned within the hour, and nobody argued. The mission was aborted and became, from that moment, a rescue.

The answer was to evacuate into Aquarius and use the lunar module as a lifeboat. It had its own oxygen, its own batteries, its own engine, and none of them depended on the ruined service module. But Aquarius had been built to support two men for two days, and it now had to keep three alive for four. Everything aboard was rationed: water above all, and power down to the last amp. As long as the crew kept the command module cold and dark, the charge in its re-entry batteries would still be there at the end — but that created a problem nobody had solved, because no one knew how to bring a frozen spacecraft back to life on a nearly depleted supply. That puzzle fell to a controller called John Aaron, who worked out a start-up sequence that had never been written down, switching things on in the exact order that would not overload what little current remained. Meanwhile the flight dynamics teams put the ship on a free-return trajectory that would swing it round the far side of the Moon, and fired the lunar module's descent engine to speed the journey home.

In Mission Control, the flight director Gene Kranz and his teams worked the problems one at a time. The deadliest was invisible. Three men in a two-man cabin were breathing out more carbon dioxide than the lunar module's scrubbers could remove, and the level was climbing towards the point at which judgement fails and, eventually, so does life. There were plenty of spare canisters — in the command module. But Odyssey's were square and Aquarius's were round, and unless the two could somehow be joined, the crew would slowly be poisoned by their own breath. So engineers on the ground were shut in a room with an exact copy of everything the astronauts had aboard and told to improvise. What they produced was a jury-rigged adapter of plastic bags, cardboard from a flight manual, tape and a sock, and its design was read up to the crew step by step over the radio. It worked; the carbon dioxide fell. Everything else stayed grim. The powered-down ship grew freezing, water condensed on the walls, the men were dehydrated and barely slept, and Haise developed a urinary infection and a fever. That ingenuity had bought them time; nothing had yet brought them home.

The last day was the worst. The command module had to be woken from the cold, and John Aaron's start-up sequence was read up and followed switch by switch, in an order that could not be varied; get it wrong and the power would collapse, and there would be no second attempt. The service module was released first, and as it drifted away the crew saw for the first time the size of the wound — an entire panel torn off, the machinery inside ruined. Then Aquarius, the lifeboat that had kept them alive for four days, was let go too: a lunar module cannot survive re-entry and would otherwise have followed them down. Odyssey hit the atmosphere alone, on battery power, its heat shield of unknown condition. Radio contact always breaks during re-entry, as ionised gas around the capsule blocks the signal, and the blackout was expected to last about four minutes. It ran longer. In Mission Control nobody spoke. Then the tracking aircraft saw the parachutes, and on 17 April 1970 Odyssey splashed down in the Pacific with all three men alive. Kranz, who had held himself together for four days, did not manage it for much longer.

What followed was not celebration but investigation. A review board chaired by Edgar Cortright took the accident apart and found, as such boards usually do, that the fault had been made long before launch by a chain of small, forgivable decisions: the dropped tank, the switches that were never upgraded to match the new ground supply, the test in which the insulation burned away unnoticed. The oxygen tanks were redesigned, the wiring protected, and an extra tank added so that a single failure could no longer take everything at once. The programme flew again the following year and went on to land four more crews. But the deeper legacy was not hardware. Apollo 13 became the standard case study in how to handle a crisis: define the real problem before reaching for a solution, work the list methodically, test the fix on the ground before anyone trusts their life to it, and never let the room be run by whoever shouts loudest. Business schools, hospitals and emergency services still teach it, under headings like improvisation, teamwork and disciplined problem-solving.

Then in 1995 the film arrived, and it fixed the story in public memory more firmly than any report could. It is a careful film in many ways, and made heroes of the flight controllers as well as the crew — but it also invented. The line most people can quote, "Failure is not an option", was written for the screen version of Gene Kranz; he never said it in 1970, though he liked it well enough to use it as the title of his memoir. The film's clean version has replaced the messier real one in most minds, which is worth noticing, because the honest lesson is less cinematic and more useful. Apollo 13 did not survive because a few brilliant individuals improvised under pressure. It survived because a very large, well-drilled organisation had spent years rehearsing for trouble it hoped would never come, and had built the simulators, the procedures and the habits of mind that made improvisation possible at all. That is the long echo: not that heroes save you, but that preparation does.